D-cycloserine is a 4-amino-1,2-oxazolidin-3-one that has R configuration. It is an antibiotic produced by Streptomyces garyphalus or S. orchidaceus and is used as part of a multi-drug regimen for the treatment of tuberculosis when resistance to, or toxicity from, primary drugs has developed. An analogue of D-alanine, it interferes with bacterial cell wall synthesis in the cytoplasm by competitive inhibition of L-alanine racemase (which forms D-alanine from L-alanine) and D-alanine--D-alanine ligase (which incorporates D-alanine into the pentapeptide required for peptidoglycan formation and bacterial cell wall synthesis). It has a role as an antitubercular agent, an antiinfective agent, an antimetabolite, a metabolite and a NMDA receptor agonist. It is an organooxygen heterocyclic antibiotic, an organonitrogen heterocyclic antibiotic and a 4-amino-1,2-oxazolidin-3-one. It is a conjugate base of a D-cycloserine(1+). It is an enantiomer of a L-cycloserine. It is a tautomer of a D-cycloserine zwitterion.